1. Field of Invention
The present invention relates to a transparent scanning apparatus of flatbed scanners to scan transparent articles such as transparent documents, films, or the like.
2. Related Art
It is well known to employ a scanner to scan a reflective article or transparent document. The difference between reflective scanning and transparent scanning is the configuration of scanning light source. If light source and a charged coupled device (CCD) are at the same side when an article to be scanned, it is defined as reflective scanning. To the contrary, if light source and CCD are at the opposite sides with respect to the article to be scanned, it is defined as transparent scanning.
It is very important to stably place an article to be scanned on a position of scanner for preventing it from moving during scanning irrespective as to whether it is done by reflective scanning or transparent scanning. It is also known that a conventional back-lighted transparency adapter is classified as independent transparency adapter and built-in transparency adapter in cover. However, both previous designs suffered from several disadvantages. For example, it is not easy to store a frame for positioning a transparent article and access the same later. Further, as a flatbed scanner, it is impossible for a transparency adapter to provide a single color of background. As such, it is usually taken a long time for a software to select a scanning area automatically by comparing the difference between the color of the background and the article. Furthermore, the surface of transparency adapter is easy to be damaged, such as scratched or collision, because it is exposed to cover. Moreover, an enclosure for a transparent article is required. This inevitably increases the volume of article.
A number of published Taiwanese patents with respect to a fixing device for a transparent document of a scanner are described below. For example, a Taiwanese Patent Published No. 294,428 entitled “Clamping device for Transparent Document of Scanner” disclosed an upper cover and a lower cover. Upper cover has an opening for defining an area. An elongate slot is adjacent the front side of the area. An elastic member is provided in the slot. Lower cover is coupled to upper cover. Lower cover has a recess for receiving a carrier. A gap is formed between the carrier and the elastic member for receiving and fastening a transparent document. However, this design is complex in components. Also, it is not easy for precisely positioning the carrier in such a narrow space. As a result, the carrier tends to slant, thus causing trouble to user. Another embodiment is disclosed in above patent in which a base is provided. The base comprises a clamp member fitted on a recess of the base. A plurality of rectangular cavities are formed on the clamp member for receiving an article to be scanned. A cover is releasably secured to the clamp member. A plurality of arc-shaped elastic pieces are formed on either side of the base. Such arc-shaped elastic pieces are in sliding contact with side rails in the scanner. The clamp member further comprises a plurality of openings each for defining a region. An inward disposed stop is formed on the side of the region. An elastic bracket is formed on the opposite side of the region. The elastic bracket has a recessed portion for receiving an article to be scanned. The article is fastened by the elastic bracket and the stop. However, this embodiment is still complex. Further, it is required to pull the clamp member from the recess of the base prior to opening the cover for changing the article while in use. This may cause inconvenience.
As to other known techniques for fastening a transparent document, a variety of frames for fixing the article are placed in a flaky cavity of transparency adapter. A rectangular frame received in the cavity by passing through the opening of the cavity is slightly smaller than the cavity in width. An opening is also provided on the rectangular frame for receiving a transparent document, a positive frame, or a negative frame. Positive frame has at least one flaky slot and a groove on the periphery of each slot for facilitating receiving and accessing the transparent document. Also, negative frame has the same configuration of flaky slots and grooves as the positive frame for facilitating operation. However, such design is disadvantageous for being difficult to place a rectangular frame in the cavity horizontally. As such, rectangular frame, positive frame, or negative frame may be slanted. Further, there is no suitable way for receiving rectangular frame, positive frame, or negative frame after scanned.
Another Taiwanese Patent Published No. 334,151 entitled “Method for Scanning Transparent Document And Frame for Fixing the Same” disclosed some components related to the present invention. For example, an opaque frame is provided. A plurality of cavities are formed on the frame. An arcuate recess is formed on the side of each cavity for ease of accessing and placing the article by hand. A transparent window in provided in each cavity for permitting light to pass through while scanning the article placed thereon. However, such design is disadvantageous for the reasons that the surface of transparency adapter is susceptible of damage (e.g., scratched or collision) due to its unflatness, and it is impossible of providing a single color of background thus causing excessive scanning time.
Still another Taiwanese Patent Published No. 361,032 entitled “Scanner Having Upper and Lower Light Sources and Moveable Blind for Upper Light Source” disclosed a scanner having an upper, a lower light sources, and a blind for blocking light emitted from the upper light source. However, such blind is provided for achieving the purpose of blocking the upper light source only. Thus it is limited in application.